zmqlibevserver

    #include <stdio.h>
    #include <stdint.h>
    #include <stdlib.h>
    #include <string.h>
    #include <stdbool.h>
    #include <ctype.h>
    #include <zmq.h>
    #include <ev.h>

    void *zmq_ctx = NULL;
    void *sock;
    bool sending = false;



    void watcher_cb(struct ev_loop *loop, struct ev_io *watcher, int revents)
    {
        uint32_t events;
        size_t opt_len = sizeof(uint32_t);

        fprintf(stderr, "Event: EV revents=%d\n", revents);
        if (EV_ERROR & revents)
        {
        fprintf(stderr, "invalid event\n");
        return;
        }

        while(1) {
        if (0 != zmq_getsockopt(sock, ZMQ_EVENTS, &events, &opt_len))
        {
            fprintf(stderr, "ZMQ_EVENTS failed\n");
            return;
        }
        fprintf(stderr, "Event: zmq_events=%d\n", events);

        if (events & ZMQ_POLLIN)
        {
            char buffer[50];
            fprintf(stderr, "Event: ZMQ_POLLIN\n");

            if (0 != zmq_recv(sock, buffer,50 ,ZMQ_NOBLOCK))
            {
            fprintf(stderr, "zmq_recv failed\n");
            return;
            }
            fprintf(stderr, "RX: %s", buffer);

            sending = true;
            fprintf(stderr, "Received packet, waiting to send response\n");
        }
        if (!sending)   // we have nothing to write
            return;

        if (events & ZMQ_POLLOUT)
        {
            //zmq_msg_t msg;
            char *buf = "A reply";

            if (0 != zmq_send(sock, buf,7, 0))
            {
            fprintf(stderr, "zmq_send failed\n");
            return;
            }
            fprintf(stderr, "TX: ");
            sending = false;
            fprintf(stderr, "Sent packet, waiting for new request\n");
        }
        }

    }

    int main(int argc, char *argv[])
    {
         int rc;
         struct ev_loop *loop;
         struct ev_io *watcher;
         int zmq_fd;
         size_t opt_len = sizeof(int);

             if (NULL == (watcher = (struct ev_io *)malloc(sizeof(struct ev_io))))
         {
          fprintf(stderr, "out of memory\n");
          return 1;
         }

         loop = ev_default_loop(0);

         zmq_ctx = zmq_init(1);

         sock = zmq_socket(zmq_ctx, ZMQ_REP);
         if (sock == NULL)
         {
          fprintf(stderr, "socket!\n");
          return 0;
         }

         rc = zmq_bind(sock, "tcp://*:5555");
         if (rc < 0)
         {
             fprintf(stderr, "bind failed\n");
             return 1;
         }

        if (0 != zmq_getsockopt(sock, ZMQ_FD, (void *)&zmq_fd, &opt_len))
        {
          fprintf(stderr, "ZMQ_FD failed\n");
          return 1;
        }

        ev_io_init(watcher, watcher_cb, zmq_fd, EV_READ);
        ev_io_start(loop, watcher);

        while(1)
        {
        ev_loop(loop, 0);
        }
        return 0;
    }